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Effects of aggregate gradation and angularity on VMA and rutting resistance
|dc.description||Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to email@example.com, referencing the URI of the item.||en|
|dc.description||Includes bibliographical references (leaves 44-48).||en|
|dc.description||Issued also on microfiche from Lange Micrographics.||en|
|dc.description.abstract||About 85 percent of hot mix asphalt (HMA) by volume and 95 percent of HMA by weight consists of mineral aggregate. The Strategic Highway Research Program (SHRP) research effort concentrated on properties and testing of asphalt binders in the development of the Superpave binder specification and mix design methology. As a result, data to assess the effects of aggregate gradation, type, and angularity on pavement performance are relatively scarce. A controversial component of the Superpave mix design process is the aggregate gradation restricted zone. It has been shown that the densest packing of aggregate particles is approximated by a straight line on the 0.45 power gradation chart. Gradations close to this line typically produce mixtures with low voids in the mineral aggregate (VMA). The restricted zone area lies along this straight line to avoid the use of these gradations with low VMA. The Superpave volumetric mix design process contains a required minimum value for fine aggregate angularity (FAA) as a function of traffic level and position of the layer within the pavement structure. This parameter is reported as the percentage of uncompacted air voids, with larger values generally indicating increased aggregate angularity and, thus, higher VMA and better resistance to permanent deformation. The purpose of this thesis is to evaluate the effects of FAA on permanent deformation in HMA mixtures containing coarse limestone and four different fine aggregates (partially crushed river gravel, crushed granite, crushed limestone, and uncrushed natural sand) using the Asphalt Pavement Analyzer (APA). Mixtures with three gradations which pass through, above, and below the restricted zone, three different mineral filler contents, and four different values of FAA were analyzed to evaluate the effects of these parameters on VMA. Based on the analysis of these tests, mixtures containing fine granite or limestone showed less permanent deformation than mixtures containing fine river gravel or natural sand. FAA values and permanent deformation did not correlate well. Gradations that pass through the restricted zone did not significantly affect mixture VMA. Mineral filler contents and FAA value did affect mixture VMA significantly.||en|
|dc.publisher||Texas A&M University|
|dc.rights||This thesis was part of a retrospective digitization project authorized by the Texas A&M University Libraries in 2008. Copyright remains vested with the author(s). It is the user's responsibility to secure permission from the copyright holder(s) for re-use of the work beyond the provision of Fair Use.||en|
|dc.subject||Major civil engineering.||en|
|dc.title||Effects of aggregate gradation and angularity on VMA and rutting resistance||en|
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